Nonmetallic corrosion-resistant enclosure for electrical apparatus

ABSTRACT

A nonmetallic corrosion-resistant enclosure for electrical apparatus comprising an outer housing or casing made from rubber or plastic material which will not deteriorate or corrode and develop leaks when exposed for an extensive period of time in a high moisture content environment.

nited States Patent 72] Inventor Dudley L. Galloway [56] ReferencesCited I N Sharpzvllle, Pu. UNITED STATES PATENTS gff fig 25 19702,366,290 1/1945 Rudd 174/15 R x {45]. Pmemed Aug lo 2,816,947 12/1957Leightner et al.. 336/90 X Assignee Westinghouse H k Corporation3,385,470 5/1968 Dorosz et a] 220/67 Pittsburgh Pa 3,406,891 10/1968Buchner et a] 220/67 X 3,434,644 3/1969 Collie 220/67 X 3,504,319 3/1970Leonard .1 336/92 X 3,511,515 5/1970 Cline etal 220/67X 5 PrimaryExaminerThomas J. KOZmfi ENCLOSURE FOR ELECTRICAL APPARATUS Attorneys-A.T. Stratton and F. E. Browder 6 Claims, 3 Drawing Figs.

[52] US. Cl 336/90, ABSTRACT: A nonmetallic corrosion-resistantenclosure for 174/50, 220/67, 336/92 electrical apparatus comprising anouter housing or casing [51] int. 1. H0lf27/02 made from rubber orplastic material which will not deteri- [50] Field ofSeaI-ch 336/90, 92,orate or corrode and develop leaks when exposed for an ex- 94; 174/17 R,17 LP, 50, 52 R; 220/85 TC, 67, 80

tensive period of time in a high moisture content environment.

PATENTED AUBI oxen SHEET 1 BF 2 INVENTOR Dudley L. Galloway FIG.

WITNESSES ATTORNEY PATE NIED AUG] 0197:

SHEET 2 OF 2 NONMETALLIC CORROSION-RESISTANT ENCLOSURE FOR ELECTRICALAPPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to nonmetallic corrosion-resistant enclosures forelectrical apparatus and more particularly to housings or casings fordistribution transformers installed in locations where the environmenthas a high moisture content.

2. Description of Prior Art 1 In the prior art it has been the practiceto provide metallic housings or casings for transformer apparatus. Thesecasings or housings are very satisfactory when the apparatus is locatedin an area where the environment atmosphere has a low moisture content.However, the present trend is to install transformers underground orpartially buried. This practice introduces problems, since inpractically all underground or partially buried installations thesurrounding atmosphere has a high moisture content. This moisture causesthe metallic housing or casing to corrode. This corrosion often developsleaks in the casing or housing. Once a leak develops in the casing orhousing the fluid coolant is lost and the transformer becomes overheatedor develops a short circuit and destroys its usefulness as atransformer. This invention overcomes the objection to the prior artmetallic housing or casing by providing a nonmetallic housing or casingwhich is highly resistant to corrosion or other effects of moisture. Thehousing or casing of the present invention is made completely ofinsulatingcorrosionresistant material, such as a plastic, for exampleepoxy, polyvinyl chloride, rubber, or other suitable plasticvmateriaLThe housing or casing of the present invention will not corrodedue to moisture and develop leaks.

SUMMARY OF THE INVENTION This invention provides a nonmetalliccorrosion-resistant housing or casing for electrical apparatus. Thecasing comprises cast or molded bottom. and top members. The bottom andtop members are cast or molded from a suitable resin, such as filledepoxy, or any other castable or moldable insulating material. A bodyportion connects to the bottom and top members to provide a container orhousing. This body portion also comprises insulation material, such asepoxy, polyvinyl chloride, rubber, or other insulating material. Thebody portion is attached to the bottom and top members by means ofdovetail slots having slanting sides. The dovetail slots receive the topand bottom of the body member and locking rings snap into the dovetailslots to firmly hold the bottom and top of the body member in thedovetail slots in the bottom and top members. The bottom edge and topedge of the body members are cemented in the dovetail slots with asuitable adhesive, such as epoxy or rubber cement, to provide afluidtight connection to the bottom and top members prior to snappingthe locking rings in place in the dovetail slots. The locking rings aremade of plastic material, such as nylon, or other suitable thermoplasticmaterial. The core-and-coil assembly of the transformer rests on thebottom member. A rigid post is connected to the core-and-coil assembly.This rigid post is connected to and supports the top member. This rigidsupport, provided by the core-coil assembly and the rigid post,maintains proper spacing between the bottom member and the top memberand prevents the body member from collapsing or otherwise deforming.Bushings for bringing the necessary conductors into the casing orhousing are mounted on the top member. A hole for receiving an eyeboltfor lifting the transformer is provided through the top member andextends into the rigid post. This hole is normally closed with aninsulating plug which is removed for insertion of the eyebolt when itbecomes necessary to lift the apparatus. A fill plug is provided in thetop member for filling the casing or housing with the required fluidcooling medium.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view ofone embodiment of a casing or housingprovided by this invention;

DESCRIPTION OF PREFERRED EMBODIMENTS Throughout the description whichfollows, like reference characters refer to like parts on each of thevarious figures of the drawing.

Referring specifically to the drawings, FIG. 1 illustrates a sideelevation view of one embodiment of a casing or housing 10 as providedby this invention. The casing or housing 10 comprises a bottom member12, a top member 14 and a body member 16 connected between the bottommember 12 and the top member 14. The members 12 and 14 are cast ormolded from nonmetallic insulating material such as filled epoxy resin,polyvinyl chloride, or any other suitable nonmetallic material that canbe readily cast or molded. The body member 16 extends between the bottommember 12 and the top member 14 and is attached to the bottom member 12and the top member 14 with a fluidtight and mechanically strongconnection. The embodiment of the casing or housing 10 shown in FIG. 1has a round cross section, however, it is understood that the crosssection of the housing or casing 10 may have any convenientconfiguration such as elliptical, round, square, or rectangular.

The bottom member 12 and the top member 14 are circular in shape andthey each example, the a dovetail groove 18 formed therein. The bodymember 16 is made of nonmetallic electrical insulating material such asepoxy, polyvinyl chloride, rubber or the like. The body member 16 may bemade of rigid self-supporting material or flexible sheet material. Thebody member 16 is attached to the bottom member 12 and the top member 14by folding the ends of the body member 16 as indicated at 20 and sealingthe ends of the body member to the inside of the dovetail grooves 18 bymeans of a good cement 19 which will provide a fluidtight seal. Forexample, the cement 19 may be epoxy sealant or room temperaturevulcanizing rubber. This cement 19 seals the edges of the body member 16to the inside of the dovetail grooves 18 to form a fluidtight jointbetween the body member 16 and the bottom and top members 12 and 14.After the edges 20 of the upper end and the lower end of the body member16 have been scaled to the inside of the dovetail grooves 18 to providea fluidtight seal, a pair of lockrings 22 and 24 are forced into thedovetail grooves 18 to provide a strong mechanical connection betweenthe body member 16 and the bottom member 12 and the top member 14.

The sealing rings 22 and 24 may be made of nylon or some other suitableresilient thermoplastic material. The ring 22 is first placed inposition and then the ring 24 is forced in position as shown moreclearly in the detail in FIG. 3. Because of the slanted sides of thedovetail slots 18, when the ring 24 is forced into position, projections26 on the outer ring 22 mate with projections 28 on the inner ring 24 toform a single interlocked ring which is tight and cannot be removed oncethe inner .ring 24 has been forced into place. Any tendency to removethe rings 22 and 24 will force the material of the body member 16tightly against the inclined sides of the dovetail slots 18 and providesa tight seal. The epoxyor room-temperature-vulcanizable rubber which isused to seal the edges of the body member 10 in the dovetail grooves 18of the end members 12 and 14 provides a fluidtight seal between the bodymember 16 and the bottom member 12 and the top member 14, and thesnap-in rings 22 and 24 provide mechanical strength for the jointbetween the body member 16 and the bottom member 12 and the top member14. ln some assemblies, a liquid therrnosetting resin or a puttylikethermosetting resin may be substituted for the locking rings 22 and 24to provide mechanical strength for the joint.

In the embodiment shown in FIG. 1, a distribution transformer comprisinga core 30 and a coil 32 is shown positioned in the housing or casing 10.The core-coil assembly comprising the core 30 and the coil 32 rests on apad 34 positioned on the bottom member 12 of the casing or housing 10. Arigid support or rod member 36 is attached to the top of the core 30 bymeans of a clamp 38. This clamp 38 may be permanently attached to thecore 30 by pressure, tack welding or any other suitable means. The upperend of the rigid rod or support member 36 is attached to the undersideof the top member 14 by means of a flange 40 and a pin 42 The rigidsupport 36 is strong enough to freely support the top member 14 from thecore 30. High-voltage bushings 44 and low-voltage bushings 46, forbringing leads into the housing or casing to connect to the coil 32, aresupported on the top member 14. A threaded hole 48 is provided throughthe top member and ex tends into the rigid post or support rod 36 forinsertion of an eyebolt 50 for lifting the transformer. Normally, theeyebolt will be removed and the threaded hole 48 closed with aninsulating plug and the plug will be removed when it is desired toinsertthe eyebolt 50 for lifting the transformer. A fill hole whichis-normally closed by an insulating plug 52 is provided in the topmember 14 for filling the transformer with liquid dielectric. y

From the foregoing description, it is seen that the embodiment of FIG. 1has provided a nonmetallic casing or housing for a distributiontransformerwherein there are no metallic parts exposed to ambientatmosphere on the outside of the casing. The core-and-coil assembly issupported on the bottom member 12 of the housing 10, and the top member14 and all of the associated bushings and other hardware mounted on thetop member 14 are supported from the core by means of a rigid post orsupport 36 connected between the core 30 and the top member 14 of thecasing or housing 10.

FIG. 2 shows sSapin second embodiment of anonmetallic casing or housingfor transformer apparatus wherein all of the parts exposed to ambientatmosphere are made of nonmetallic material. The embodiment of FIG. 2comprises a top member 14 similar to that disclosed forFIG. 1. However,in FIG. 2 a

, metallic casing comprising sides 60 and a bottom member 62 is attachedto the nonmetallic top member 14. In addition to the inner housing orcontainer comprising the metallic sides 60 and-the metallic bottom 62,the inner container is surrounded by an outer container 62. The outercontainer 62 is made from some plastic material such as epoxy, polyvinylchloride, rubber or other suitable plastic material. The top member 14of this embodiment is also provided with a dovetail slot 18. The upperedge of the nonmetallic housing member 62 is fastened in the groove 18by means of an adhesive and a pair of snap-in rings 22 and 24 in amanner similar to that described for the embodiment of FIG. 1. Thisconnection provides a fluidtight and mechanically strong connectionbetween the top member 14 and the outer nonmetallic housing 62. Theembodiment of FIG. 2 in all other respects is identical to thatdescribed hereinbefore for FIG. 1. However, it is stated hereinbeforethat the inner housing comprising a body member 60 having a bottom 62 ismade of metal, it is understood that this body member may also be madeof filamentwound glass-epoxy or any other suitable resinous material. Inthe embodiment of FIG. 2 the cross section of the housing or tainer orhousing. Y

From the foregoing description taken in connection with the drawings, itis seen that this invention has provided a nonmetallic,corrosive-resistant, housing or casing for a distribution transformerwhich may be installedin an environment where the atmosphere contains alarge quantity of moisture or other agents which would cause corrosionof metals. Since the entire exposed surface of the tank or casingprovided by this invention is made of nonmetallic corrosive-resistantresinous materials, the housing or casing will resist deteriorationbecause of the moisture better than the metallic tanks used in the priorart, and will cause less trouble and outages due to corrosion of thehousings or casings for transformers installed in areas which wouldnormally subject the metallic prior art housing or casing to rapidcorrosion.

I claim as my invention:

1. A housing for electrical apparatus comprising a nonmetallic bottommember, a nonmetallic top member, a nonmetallic body member extendingbetween said bottom member and said top ember and means providing afluidtight and mechanically strong connection between said body memberand said bottom member and between saidtop member and said bodymember toprovide a fluidtight enclosure, said means for providing a connectionbetween said body member and said top and bottom members comprises adovetail slot having slanting sides in said bottom member and said topmember with the edges of the bottom end of said body member sealed totheinside slanting walls of said dovetail slot in said bottom memberwith an adhesive and with the edges of the upper end of said body membersealed to the inside slanting walls of said dovetail slot in said topmember, said adhesive providing a fluidtight seal between said bottommember and said body member and between said top member and said bodymember and means positioned in said dovetail slots in said bottom memberand said top member to provide mechanical strength for the jointsbetween said body member and said d bottom member and said top member.

2. The apparatus of claim 1 wherein said means positioned in saiddovetail slots comprises a snapring means.

3. The apparatus of claim 2, wherein said snapring means comprises aninner ring having a slanted side corresponding to the slanted side ofsaid dovetail slot and an outer ring having a slanted side correspondingto another slanted side of said dovetail slot.

4. The apparatus of claim 3 wherein said inner snapring and said outersnapring have interlocking projections.

5. The apparatus of claim 1 wherein said means position in said dovetailslots comprises therrnosetting resin.

6. The housing as claimed in claim 1 having a core-and-coil assemblypositioned therein with the core-and-coil assembly resting on saidbottom member and a rigid support extending from said core and attachedto said upper member to support said upper member in fixed relationwithrespect to said bottom member.

2. The apparatus of claim 1 wherein said means positioned in saiddovetail slots comprises a snapring means.
 3. The apparatus of claim 2,wherein said snapring means comprises an inner ring having a slantedside corresponding to the slanted side of said dovetail slot and anouter ring having a slanted side corresponding to another slanted sideof said dovetail slot.
 4. The apparatus of claim 3 wherein said innersnapring and said outer snapring have interlocking projections.
 5. Theapparatus of claim 1 wherein said means position in said dovetail slotscomprises thermosetting resin.
 6. The housing as claimed in claim 1having a core-and-coil assembly positioned therein with thecore-and-coil assembly resting on said bottom member and a rigid supportextending from said core and attached to said upper member to supportsaid upper member in fixed relation with respect to said bOttom member.